This invention relates to an image forming apparatus of the type which is separable into upper and lower units and more particularly to such an image forming apparatus having a paper cassette in the lower unit such that each sheet discharged from the cassette changes the direction of its motion and is transported then to a processing section in the upper unit for processing.
There are image forming apparatus which are separable into upper and lower units, the lower unit containing a paper cassette and a paper turning member for turning a sheet of paper discharged from the cassette to change the direction of its motion, the upper unit containing a processing section for image formation, and a paper transporting route being formed along the boundary between the upper and lower units. The upper and lower units of such an apparatus are separable and the paper transporting route can be opened up such that when there is a jamming in the paper transporting route, the jammed paper can be easily removed. If a jamming takes place in the neighborhood of the paper turning member, however, the jammed paper cannot be removed merely by opening the upper unit. For this reason, conventional image forming apparatus of this type were structured such that a paper turning member near the paper cassette can also be opened up.
In FIGS. 5A and 5B, which show a conventional image forming apparatus 1 of the type separable into an upper unit 1a and a lower unit 1b as described above, a paper cassette 2 is removably inserted into the lower unit 1b such that sheets of paper are discharged from its right-hand end. On the right-hand side of the paper cassette 2 and adjacent thereto is a paper turning member 3 having a curved (concave) guiding surface 3c. The upper unit 1a is rotatably supported by the lower unit 1b around an axis P above the paper turning member 3 such that the apparatus can be opened by separating the upper and lower units through an opening for ejecting the processed paper. The paper turning member 3, in turn, is rotatably supported by the lower unit 1b around another axis Q at the lower part thereof such that the paper turning section can be opened up from above. A sheet discharged from the paper cassette 2 is turned over by this paper turning member 3 and transported to the processing section inside the upper unit 1a through a transporting route 4 formed along the boundary between the lower unit 1a and the upper unit 1b.
If a sheet thus being transported from the paper cassette 2 becomes jammed, the operator opens the upper unit 1a in the upward direction or the paper turning member 3 in the downward direction. Although FIG. 5b shows both the upper unit 1a and the paper turning member 3 in the opened conditions, the operator has only to open the upper unit 1a if the jamming is on the paper transporting route 4. Likewise, the operator has only to open the paper turning member 3 if the jamming is near its position. With a conventional apparatus structured as shown in FIGS. 5A and 5B, however, the operator cannot immediately ascertain whether the jamming has occurred on the paper transporting route 4 or near the paper turning member 3. In other words, it is frequently the case that the operator must open up both the upper unit 1 and the paper turning member 3. Although attempts have been made to provide means for informing the position of a jam to the operator, sensors for detecting the position of a jam, display means for displaying this information and control means for controlling these additional devices add to the overall cost of the apparatus.
A conventional image forming apparatus of another type is illustrated in FIGS. 6A and 6B wherein components which are equivalent or similar to those shown in FIGS. 5A and 5B are indicated by the same numerals. This apparatus is characterized as having the paper turning member 3 unistructurally formed on the paper-discharging end of the paper cassette 2 and the upper unit 1a rotatably supported by the lower unit 1b around an axis near the opening through which processed paper is ejected. With an apparatus of this structure, the curved guiding surface 3c is opened when the paper cassette 2 is pulled forward together with the paper turning member 3. Neither with this apparatus, however, can the operator ascertain immediately whether the jamming is on the paper transporting route 4 or near the paper turning member 3 unless a detector, etc. are provided at an increased cost.